LOL......yes, some people would take the view that anything they come up with is the answer, no matter how ridiculous, and if you point out the shortcomings they get very annoyed and list you as a troll etc.

The ball screw solution is not a simple one. but it does demonstrate that many solutions can fit other problems too.

The biggest problem to overcome is the fact that the screw is a relatively soft material and the principle of the ball screw is a rolling one.......that means hard metal on hard metal.......have one of the pair soft and it gets "transformed/reformed" by the other.

The problem is centred around the need to provide a backlash, frictionless drive that will economically replace the ballscrew for DIY purposes.

The drive you showed will work within it's limitations provided the load is proportional to the strength of the materials, namely the softness of the screw, which is usually available off the shelf or already on a machine.

When it's on a machine it drives the table, whatever, by sliding the flanks against a sacrificial bronze nut.....the nut being the easiest part to replace......and that is the problem......the design of the screw will not be practical if you roll it against a hardened surface....getting reformed in the process.

If by some magical process the screw could become hard without changing the dimensions of the very precise pitch and linear straightness, then the internal race of the bearing you showed would drive against the hard screw flanks, actually on the corners only, but without proper lubrication would both eventually grind themselves to dust.....this is like a ballrace that has no lubrication in it.....it will roll freely for a while until the tracks and balls pit and destroy each other......add some lubrication and the set-up would probably last for a longer time, relative to the load applied to it.

The process of hardening a soft screw still leaves it with a soft core that would not last long under the conditions I stated, but within a certain load factor would probably be very friction free and last forever...IE, a hand driven device.

The device you thought of is as simple as you can devise it, but the moment you change the status of the screw by hardening it, other factors arise and so you get into a "chase my tail" scenario trying to eliminate all the problems as they occur.......the ballscrew solves all the problems except the cost factor.

The making of a ballscrew alternative is also relative to the cost of the labour hours to produce it, and taken purely as a labour/hour cost factor, the ballscrew is the winner all the way, and totally readily available off the shelf for retrofit purposes.
Ian.